1. Field of the Invention
The present invention relates to small internal combustion engines of the type used with lawn mowers, lawn and garden tractors, snow throwers and other implements, or with small sport vehicles. Particularly, the present invention relates to small engines having a diaphragm-type fuel pump which is actuated by pressure pulses created within the engine crankcase when the engine is running.
2. Description of the Related Art
A typical internal combustion engine has an engine housing, including a crankcase containing an oil sump for receiving lubricating fluid or oil introduced through an oil fill conduit attached to the engine housing. The engine also includes a fuel supply system such as a fuel pump for pumping fuel from a fuel tank to a carburetor, where the fuel is mixed with air to form a fuel/air mixture for combustion. A common fuel pump includes a diaphragm which is reciprocated by pressure pulses generated within the crankcase during running of the engine, a fuel inlet for receiving the fuel from the fuel tank, and a fuel outlet for passing the fuel to the carburetor.
According to a known engine configuration shown in FIG. 1, an internal combustion engine 10 includes an engine housing 33 with crankcase 40, which contains oil sump 32 for receiving oil. Engine 10 further includes an oil fill tube 35 in communication with oil sump 32, wherein oil can be poured through oil fill tube 35 into oil sump 32. Engine 10 includes a diaphragm-type fuel pump 31 mounted to engine housing 33 with a fastener or a mounting bracket 14. Fuel pump 31 includes a pump assembly 36 having a fuel inlet 48 in communication with a fuel tank 46 by means of a fuel inlet line 49, and a fuel outlet 52 in communication with an air/fuel mixing device 44 such as a carburetor or a fuel injector, for example, by means of a fuel outlet line 53. Engine 10 further includes a pulse line 16 having a first end 26 and a second end 27. First end 26 of pulse line 16 is fastened with a first clamp 18 to a connection port 17 of crankcase 40, and second end 27 of pulse line 16 is connected to a pulse inlet 15 of pump assembly 36 by a second clamp 19, wherein pulse line 16 communicates pump assembly 36 with connection port 17 and crankcase 40.
In operation, when engine 10 starts to run, pressure pulses are created within crankcase 40 due to reciprocation of the piston (not shown) within the engine cylinder. The pulses are communicated from connection port 17 of crankcase 40 through pulse line 16 to actuate a diaphragm (not shown) within pump assembly 36, which reciprocates to draw fuel from fuel tank 46 through inlet line 49 into pump assembly 36, followed by driving the fuel from pump assembly 36 through fuel outlet line 53 to air/fuel mixing device 44.
Japanese Patent No. JP 403217652A discloses an engine including an engine housing containing a crankcase, an oil fill tube attached to the engine housing, and a fuel pump separately attached to the engine housing. The engine further includes a separate, dedicated pulse line connecting a pulse port of the oil fill tube to the fuel pump, such that crankcase pressure pulses are communicated to the fuel pump through the oil fill tube and the pulse line.
In each of the above configurations, a separate pulse line is required for communicating pressure pulses from the crankcase to the fuel pump. Further attachment components needed for the foregoing configurations include a bracket for fastening the fuel pump to the engine housing, a first clamp for fastening the pulse line to the fuel pump, and a second clamp for fastening an opposite end of the pulse line either to a connection port of the crankcase or to a pulse port of the oil fill tube.
It is desirable to simplify the forgoing fuel pump configuration in order to reduce the total number of parts used, as well as the labor required for assembling same.
The present invention provides an internal combustion engine with an engine housing containing an oil sump in fluid communication with an oil fill conduit, and a fuel pump including a pump assembly having at least a portion thereof formed integrally with the oil fill conduit and in fluid communication therewith. The fuel pump is actuated by pressure pulses created within the engine crankcase when the engine is running, which are communicated to the fuel pump through the oil fill conduit.
The engine may have a shroud attached to the crankcase and covering at least a portion thereof. Optionally, a bracket may be integrally formed with the oil fill conduit which, along with a fastener, is used to attach to the oil fill conduit to the shroud of the engine or other suitable engine structure.
The fuel pump includes a pump assembly having a pump housing and a diaphragm therewithin, which is actuated by pressure pulses generated within the engine crankcase during running of the engine. The portion of the fuel pump which is integrally formed with the oil fill conduit further includes a pulse passage to communicate the fuel pump with the interior space of the oil fill conduit. The pulse passage extends upwardly from an interior wall of the oil fill conduit to prevent oil from entering the pulse passage when oil is filled through the oil fill conduit into the oil sump.
The fuel pump housing further includes a fuel inlet in fluid communication with a fuel tank, and a fuel outlet in fluid communication with an air/fuel mixing device. The fuel pump is operable to pump fuel from the fuel tank to the air/fuel mixing device. Specifically, the engine may include a fuel inlet line communicating the fuel tank with the fuel inlet, and a fuel outlet line communicating the fuel outlet with the air/fuel mixing device.
Advantageously, the present invention, in integrating at least a portion of the fuel pump with the oil fill conduit, obviates need for a pulse port on the crankcase and a separate pulse line, as well as a plurality of clamps used to fasten the pulse line to the crankcase and to the fuel pump, thereby reducing the number of parts used in the fuel supply system of the engine and the manufacturing steps needed to assemble the engine.
In one form thereof, the present invention provides an internal combustion engine, including an engine housing containing an oil sump therein; an oil fill conduit in fluid communication with the oil sump; and a fuel pump including a pump assembly, at least a portion of the pump assembly integrally formed with the oil fill conduit and in fluid communication therewith.
In another form thereof, the present invention provides an internal combustion engine, including a crankcase containing an oil sump therein; an oil fill tube attached to the crankcase in fluid communication with the oil sump; a fuel pump including a pump assembly, at least a portion of the pump assembly integrally formed with the oil fill tube and in fluid communication therewith; and a diaphragm disposed within the pump assembly, the diaphragm actuated by pressure pulses generated within the crankcase during running of the engine, the pressure pulses communicated to the pump assembly from the crankcase through the oil fill tube.
In a further form thereof, the present invention provides an internal combustion engine, including a crankcase containing an oil sump therein; at least one cylinder connected to the crankcase; a crankshaft rotatably carried within the crankcase; a least one connecting rod and piston assembly coupled to the crankshaft, the at least one piston reciprocable within a respective the cylinder to generate pressure pulses within the crankcase; an oil fill tube attached to the crankcase in fluid communication with the oil sump; and a fuel supply system for the engine, including a fuel tank; a carburetor; a fuel line connecting the fuel tank with the carburetor; and a fuel pump in disposed within the fuel line, the fuel pump including a pump assembly having a diaphragm therein, at least a portion of the pump assembly integrally formed with the oil fill tube and in fluid communication therewith, wherein the diaphragm is actuated by the pressure pulses to pump fuel from the fuel tank to the carburetor.
In a still further form thereof, the present invention provides a fuel pump and oil fill tube assembly, including an oil fill tube; and a fuel pump, at least a portion of the fuel pump integrally formed with the oil fill tube and in fluid communication therewith.